Glass edge working machine



J- C. OGLE ET AL GLASS EDGE WORKING MACHINE Sept. 7, 1954 8 Sheets-Sheet 1 Filed June 15, 1949 m y A N @N QM Mow n I mom lomwp r Fm N3 m m l w mww .1. c. OGLE ET AL 2,688,214

GLASS EDGE WORKING MACHINE 8 Sheets-Sheet 2 .1 h 6 Am V E Sept. 7, 1954 Filed June 15, 1949 P 7, 1954 J. c. ecu: mm.

GLASS EDGE WORKING MACHINE 8 Sheets-Sheet 4 Filed June 15, 1949 Y Sept. 7, 1954 J c, OGLE ET AL GLASS EDGE WORKING MACHINE 8 Sheds-Sheet 5 Filed June 15, 1949 vQoN me/L 6. (9 gawk wegfy -WNJ. $3 mwu n? P? g fl 3 on x P 7, 1954 J. c. OGLE ETAL 2,688,214

GLASS EDGE WORKING MACHINE Filed June 15, 1949 8 Sheets-Sheet 6 J. c. OGLE ET AL 2,688,214

GLASS EDGE WORKING MACHINE Sept. 7, 1954 8 Sheets-Sheet 7 Filed June 15, 1949 3nventor$ med (1 fe and 9.15 27% fzfz Sept. 7, 1954 Filed June 15. 1949 J. C. QGLE ET AL GLASS EDGE WORKING MACHINE 8 Sheets-Sheet 8 J1 E 544 125 MA I 126 5 Patented Sept. 7, 1954 GLASS EDGE WORKING MACHINE James C. Ogle and James F. Jordan, Brackend e, 131a,, assignors to Libbey-Owens-Ford Glass Company, Toledo, Ohio, a corporation of Ohio Application June 15, 1949, Serial No.'99,218

(Cl. 51+-10l) 10 Claims. 1

The present invention relates broadly to a grinding machine vfor working the edges of plates of glass or other materials and more particularly to an improved apparatus for edge grinding and/or beveling plates to a predetermined contour.

Although it is to be expressly understood that the grindi g machine herein provided is not limited to any specific use, it has been designed primarily for and is of especial utility in the edging of so-called glass mirror plates which are used in the manufacture of rear view mirrors for automotive vehicles and the like. There- .fore, while the invention will be more particularly hereinafter described in connection with the edging and/or beveling of glass plates, it may be also used for working the edges of plates of other materials.

An important object of the invention is the provision of a grinding apparatus of novel and improved construction for finish edging and/or beveling plates of glass or other materials rapidly, accurately and economically and with a minimum of handling and also a minimum amount of effort and attention on the part of the operator whereby uniformly contour ground plates with well finished surfaces may be secured.

Another important object of the invention is the provision of a grinding apparatus particularly adapted for working the rough edges of glass blanks of different sizes and/or differing contours to a predetermined outline and with a desired smoothness of finish, While simultaneously producing a ground bevel along the edges of the blanks if desired.

Another object of the invention is the provision of grinding apparatus embodying a novel form of work holder for supporting and firmly securing the glass plates in position to be operated upon and being of such construction that the edges of the plates may be simultaneously contour ground and beveled without the necessity of removing them from the work holder or changing the relative position thereof.

Another object of the invention is the provision of grinding apparatus embodying a pair of grinding units operating about substantially vertical axes together with a work holder rotatably mounted between the grinding units .for supporting the glass plate to be ground in asubstantially horizontal position, together with means for automatically controlling the rotation of the work holder and the movement of the grinding units toward and away therefrom.

Another object of vthe intentionis the previ- 2 sion of a din app r tu embo y ng a ratuum system associated with the rotatable .wgrlr holder to secure the glass plate thereon, and a semi-automatic control system manually openable after each grinding operation to first disconnect and subsequently connect the vacuum system to the work holder before starting the rotation of said WQl'khOldQl for the next grinding .cycle.

Another object of the invention is the provi sion of a grinding apparatus embodying a template for controlling the movement of the grinding units relative to the glass plate during grinding in such a way that the amount of material removed from the edges thereof is definitely and automatically controlled and is not dependent upon the skill of an operator.

A further object of the invention is the provision of a grinding apparatus comprising a pair or" movable grinding units and a rotatable work holder located between said grinding units and having a template associated therewith, menu, ally operable means being provided to move the grinding units into engagement with the template to start the grinding operation and mechanically operable for movement out of engagement with the said template to stop the grindingoperation.

A further object ,of the invention is the provision of a r ndin app ratus mb yin span of movable grinding units and a rotatable work holder having a template associated therewith, and which apparatus further includes a power driven cam means, and a semi-automatic control system manually operable to start rotation of the work holder and cam means, said cam means causing movement of the grinding units into and out of engagement with the template at the beginning and end of the grinding cycle and further acting to automatically open the said control system when-the grinding units have been moved out of engagement with the template to bring the machine to a stop.

A further object of the invention is the provision of a grinding apparatus which embodies a pair of movable grinding units and a rotatable work holder interposed between the grinding units and having a template associated there.- with, and in which means is provided for reciprocally moving said grinding units with respect to the workholder, together with a vacuum system associated with the work holder for securing the work thereon, manually operable means for controllingthe yaouum system and :ior preventing rotation oi the work holder and movement of the grinding units into engagement with the template until the work is vacuously secured on the work holder, and means for automatically stopping rotation of the work holder when the grinding units have been moved out of engagement with the template.

A still further object of the invention is the provision of a grinding apparatus comprising a pair of movable grinding units and a rotatable work holder having a template associated therewith, a vacuum system associated with the work holder for securing the work thereon, a control cam for the grinding units, power means for driving the work holder and control cam at a different ratio of speed, and a semi-automatic control system manually operable to initially disconnect and then connect the vacuum system to the work holder after each grinding cycle and prior to the beginning of the next grinding cycle, said control cam being adapted to move the grinding units into engagement with the template while the same is rotating and to remove said units from engagement with said template when the grinding cycle has been completed, the said control cam acting to automatically open the control system when it has caused movement of the grinding units out of engagement with the said template to bring the machine to a stop.

A still further object of the invention is the provision of a grinding apparatus embodying grinding wheels rotatable about substantially vertical axes, a work holder being rotatably mounted between the grinding wheels for supporting the plate to be ground in a substantially horizontal position, with means for moving the grinding wheels in unison toward the plate and for controlling the time they are in engagement with the said plate so that during the grinding cycle established for the apparatus, the plate will be rotated more than one complete revolution, thereby effecting an overlap of grinding action and assuring that the desired pattern will be reproduced without any roughness appearing at the initial point of grinding.

Other objects and advantages of the invention will become more apparent during the course of the following description, when taken in connection with the accompanying drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the same:

Fig. 1 is a front elevation of an edge grinding machine constructed in accordance with the present invention;

Fig. 2 is a detail view of the controls of the machine;

Fig. 3 is an end view of the machine;

Fig. 4 is a perspective view of the work supporting means showing a rough glass blank to be ground carried thereby;

Fig. 5 is a perspective view of a finished glass plate;

Fig. 6 is a diagrammatic view illustrating the machine operation;

Fig. 6A is a diagrammatic View showing the relative positions of the two cams which control the inward and outward movements of the grinding units relative to the work holder;

Fig. 7 is a plan view of the machine;

Fig. 8 is a horizontal section taken substantially on line 38 of Fig. 1;

Fig. 9 is a view similar to Fig. 8, but showing the machine control elements arranged at a midway point in their operating cycle;

Fig. 10 is a detail section taken substantially on line l0|0 of Fig. 9;

Fig. 11 is a detail section taken substantially on line l|ll of Fig. 9;

Fig. 12 is a detail section taken substantially on line l2-l2 of Fig. 9;

Fig. 13 is a top view, partly in section of a portion of the cam following mechanism;

Fig. 14 is an enlarged vertical section taken substantially on line I4l4 of Fig. 3;

Fig. 15 is a detail section taken substantially on line [5-45 of Fig. 14;

Fig. 16 is an enlarged section taken substantially on line [6-46 of Fig. 14;

Fig. 17 is a detail section taken substantially on line l1--ll of Fig. 16;

Fig. '18 is a vertical transverse section through the glass plate supporting means and rotary driving assembly therefor;

Fig. 19 is a top view of the glass plate supporting means;

Fig. 20 is a horizontal section taken substantially on line 2020 of Fig. 18;

Fig. 21 is a perspective view of the template cams and the mounting therefor;

Fig. 22 is a diagrammatic illustration of the electrical system for the grinding machine; and

Fig. 23 is a detail view showing two different forms of edge grinding wheels.

Referring now to the drawings, there is illustrated a grinding machine, generally designated by the letter A and which, as pointed out above, is primarily designed for edging and/or beveling glass blanks to exact, predetermined dimensions as established by suitable template or pattern forms, although it is not restricted to such use. This machine is capable of edging glass blanks in the form of plates having a variety of dimensional sizes and of differing contours, such as substantially square, rectangular, circular, elliptical and/or combinations thereof.

It is customary in the fabrication of automobile rear view and vanity mirrors, as well as in similar and other conventional type mirrors, to mount the silvered or other coated glass plate in a metal frame or casing which is prestamped to the desired shape and size and subsequently assembled with the mirrored glass plate. Because of this, it is essential that the glass plate, to which the mirrored coating is to be applied, conform to the exact shape and size of the metal frame or casing and have suitably finished edge surfaces. With the grinding machine of this invention, it is possible to produce both the edge outline and, if desired, a bevel along one corner of the glass plate simultaneously, the edge outline being exactly ground to reproduce the outline or form of a master template or pattern in duplication of other and like glass plates. The desired angle of bevel or chamfer may be modifled according to demands of the finished article by merely changing the angle of the grinding element. Thus, the glass plate 13, shown in Fig. 5 as representative of the many combinations of dimensions and contours, is, in this particular instance, rectangular and has a vertically disposed edge surface C, ground to the dimension of a corresponding template, and a beveled upper corner surface indicated at D.

Referring particularly to Fig. 1, the grinding machine A embodies a pair of self-contained grinding units, generally indicated at E and F, said units being operatively associated with driving and/or control elements contained within the main framework of the machine. In accordance with the invention, the unit E is provided with a grinding wheel G adapted to finish grind or edge the periphery of a glass blank as indicated at C in Fig. 5, while the other unit F has a grinding wheel H dressed to simultaneously produce the bevel or chamfer D at the upper corner of the blank.

The grinding units E1 and F are mounted at opposite sides of a rotatable work supporting carriage I upon which the glass blank J to be ground is carried. The grinding units are mechanically interconnected so that they move in unison through one operating cycle while the glass supporting carriage I is rotated through substantially one and a half revolutions. the grinding units toward the glass blank and the subsequent return to their idle positions, is accomplished within a portion of a half revolution of the glass supporting carriage I, thereby assuring completion of the grinding cycle with a continuance of grinding, or overlap, along and beyond the initial area of engagement of the grinding wheels G and H and the glass blank J to eliminate any possibility of incomplete edging. During the inward movement of thegrinding units E and F, the glass blank J is revolved from its position of loading until engagement of the grinding wheels therewith has been effected and further approaching movement of said grinding units is monitored by the control elements of the grinding machine.

Broadly speaking, the cyclic operation of the grinding machine is semi-automatic; operation of the grinding units E and F being initiated when the glass blank J has been loaded upon the supporting carriage I and subsequently being halted automatically upon the completion of the grinding cycle. As will be more fully hereinafter set forth in detail, the glass blank J is firmly held upon the supporting carriage I by vacuum and is removable therefrom when such vacuum is destroyed. This is accomplished by the operator who actuates suitable controls generally indicated at K, for the vacuum and machine system, and upon the release of which the vacuous condition will be reestablished and operation of the machine initiated.

With reference now more specifically to the constructional details of the grinding machine A, it will be noted throughout the several assembly views that the supporting frame of the machine comprises an upper, rectangular, traylike platform 2! arranged above the base 22 and supported by pairs of corner pillars 23 and '24. The pillars 23 are disposed in the corners at one end of the base 22 while the pillars 24 are disposed in the opposite end corners. The pillars 24 are somewhat shorter than pillars 23 due to the provision of a reservoir 25 within the base 22 for storage of liquid coolant. Located substantially midway between the platform 2| and base 22, is a horizontal shelf 26 supported at one end on legs El and at the opposite end by an angle brace 28 secured to the corner pillars 2 1. Suitable closure panels 29 may be secured to the pillars 23 and 24 to enclose the sides and ends of the framework 28 and, if desired, a splash guard 35 may be carried by the platform 2| as shown in Figs. 1 and 3, said guard being supported by clips 3i that engage the upper edges of the side wall 32 of the platform, the bottom of which is designated 33.

The bottom 33 of the platform 2| is provided with aligned openings 34, 35 and 36 (Figs. '7 and 14) which are formed to receive the carriages Movement of of the grinding units E. and F and the spindle assembly, generally designated at 3i, for rotation of the supporting carriage I. The openings 34 and 36 are covered by slide housings 38 having elongated passageways 39 formed therein and bounded by the vertically rising walls it through which the body portions of the carriages ti and 42, for the grinding units E and F respectively, extend and move in their reciprocal travel. The carriages 4i and d2 are composed of identically component parts, usually termed right or left hand as the case may be. For brevity of description, only the right hand carriage 42, shown in detail in Figs. 14 and 16, will be described but it will be understood that the description of said carriage applies equally as well to the opposite or left hand carriage M.

As illustrated in Figs. 14 and 16, the carriage 4'2 is composed of a base member 43 and a vertically disposed riser member 44 which extends through the passageway 38 and on which the motorized grinding unit F is mounted. The base member 43 and riser member 44 are secured together by machine screws or the like M and the said base member is supported for longitudinal movement between the depending wall portions 45 of the housing 3% by means of ball bearing assemblies 46 (Fig. 16). These bearing assemblies comprise a pair of rail sections ll and 4B and a series of balls 43. More particularly, the rail section it? of each bearing assembly 46 is secured to the depending wall id of housing 38, while the component rail section id is secured to the side wall of the base member 43. The inner opposed surfaces of these rail sections have V-shaped grooves 58 formed therein in which the balls :39 are located. The balls are confined by a cage or suitably apertured plate 54, and to prevent escape of the balls from either end of the rail sections, retainer plates 52 are aiiixed to the ends of the rail sections 38 as shown in Fig. 3, to engage one end or the other of the plates 5|.

The riser member id, which is carried by and movable as a unit with the base member 43, has an upwardly extending wall 53 received within the passageway 39 of the related slide housing 38. The wall 53 is reenforced by vertical transverse fianges 54 and is provided with a horizontally disposed top 55 having a peripheral flange or skirt portion 56 which projects downwardly over the upper portion of the wall' ifl of housing 38. The peripheral flange 5'5 coacts with the rising wall 40 of housing 38 to enclose the passageway 39 and prevent entrance and drainage of escaping coolant as it is thrown by the grinding wheels G and H. As shown in Fig. 14, the top 55 is of suflicient length to permit adequate longitudinal movement of the carriage d2 relashown in Figs. 14 and 16, provided with a horizontally undercut guideway 53 in which is mounted .a supporting member 59 for the motorized grinding spindle assembly (ill (on the right hand) of the grinding unit F. The supporting member 59 is formed of separable though rigidly interconnected members, namely, a slide member 6| 7 and a bracket member 62. The slide member 6| has beveled upper and lower edges 63 and 64, respectively, received in the guideway 58, and a laterally disposed flange 65 to which the bracket member 52 is connected by bolts or the like 66 and 61. The beveled upper and lower edges 63 and 64 of the slide member 6| engage the corresponding undercut surfaces 68 and 66 of guideway 58, and the undercut surface 69 is preferably formed on a gib plate I6 which is located in and secured to the guideway 58 when the parts are assembled.

The bracket member 62 has a corresponding flange plate II which is axially drilled, as at I2, to receive a horizontal shaft 13 which is carried in the flange 65 (Fig. 1'7) and is rigidly secured therein by a set screw 14. Since the shaft I3 is loosely received within the opening 12 in flange plate TI, the said flange plate may be shifted angularly with respect to the said flange 65 to effect the desired angular adjustment of the grinding unit relative to the work. To secure the flange plates 65 and ll in rigid relation and yet permit such angular movements as become necessary, the said flange plates are provided with arcuate slots 75 and i6, respectively, the bolts 66 and 61 extending loosely therethrough and threaded into the opposed flange plates. Carried by the bracket member 62 is a vertically disposed clamping collar I8 which receives the annular portion I9 of the grinding spindle assembly 66 and which is secured therein by screws 86. The position of the bracket member 62 with reference to the slide member 6| may thus be corrected to maintain the grinding unit in vertical position by shifting the member 62 angularly to the member 6| upon loosening the bolts 66 and '61 and swinging the bracket member 62 upon the shaft I3 with reference to the slide member 6|.

The member 6| is slidable within the guideway 58 to move the motorized grinding spindle assembly 66 toward and away from the work holder I. For this purpose, there is provided a block 8| secured to the slide member 6| and extending through a rectangular aperture 82 formed in the vertical wall portion 83 of the guideway 58. The block BI is drilled and tapped as at 84 to receive a regulating and adjusting screw 85 which is turnable by a handle 86. The screw 85 has a shank portion 8! journaled in ribs 88 extended from the wall 63. To prevent endwise movement of the screw 85, there is provided a collar 89 which is secured to the shank portion 81 between the ribs 86. Upon rotation of the screw 85, the block 8| will be moved along its threaded portion and consequently the slide member 6| will be adjusted to any required position by longitudinal movement in the guide- Way 58.

Provision is made for locking the screw 85 against rotation to secure the parts in predetermined fixed position by means of a clamping shaft 96 located in the block 8| at right angles to the screw 85. The shaft 96 has a threaded end 9I and a handle 92 secured at its opposite end. The threaded end 6| is received in a tapped hole 93 formed in the block 8| and slide member 6|. To effect a clamping relation between the block 8| and screw 85, the block BI is slotted to provide jaw portions 64 in alignment with and extending through the tapped hole 84 so that upon rotation of the shaft 96, the handle 92 will be urged against the outer surface of the block with sufficient thrust to compress the jaws 94 and thereby firmly grip the screw 85.

By releasing the handle 92 and turning the handle 86 of adjusting screw 85, the slide member 6| of either grinding unit E and/or F can be moved within the guideway 58 and the grinding spindle assembly 66, carried in bracket member 62, will be extended or retracted so that the grinding wheel G and/or H mounted thereon can be initially located with reference to the work supporting carriage I. Each of the grinding units E and F is thus provided with adjusting and/or compensating means for positioning of their respective grinding spindle assemblies 66 to the end that said assemblies will be properly disposed with reference to the glass carriage I and also be suitably supported in a vertical plane.

The spindle assembly 31 of the work supporting carriage I is interposed between the grinding units E and F so that the glass or other work blank J, which is carried on said supporting carriage I, will be ground along its edge portions as the grinding units are urged, thereagainst, as will be more fully hereinafter described. The spindle assembly 31 is composed of two aligned shafts 95 and 66 that are keyed together at their adjoining ends and supported to rotate as a unit. As shown in Fig. 18, the shaft 95 is journaled in spaced bearings 91 supported in the opposite ends of a casing 69 mounted on the shelf 26 and enclosed by cap plates 99. The shaft 96 is arranged above shaft 95 and has annular shoulders I66 formed in its surface for receiving the inner cones of roller bearings I6 I. The outer races of the bearings I 6| are contained in fitting end portions I6I of a housing I62. The housing I62 constitutes a centrally disposed part of a cover plate I63 which has an annular rim I64 fitting within the opening 35 in the floor 33 of platform 2|.

The shafts 95 and 96 are connected together at their inner ends by a plate assembly shown in Figs. 18 and 21, and which comprises end plates I65 and I66 and intermediate cam plates I61 and E68 which constitute one cam control assembly for governing the movements of the grinding units E and F.

The end plate I85 is secured by screws I69 to the end of the shaft 96 and is provided with a centering plug IIil received in a recess or socket III in said shaft. The plate I65 also has a depending axial sleeve portion II2 on which the cam plates I67 and I68 and the end plate I66 are centrally aligned. The sleeve II 2 extends beyond the end plate I66 and is received within the socket H3 in the shaft 95. The openings in the plug I I6 and sleeve portion I I2 align with and form continuations of the axially formed bores H4 in the shafts 85 and 96 to extend from one end to the other of the spindle assembly 31.

The end plate I65 is drilled to receive screws II5 which extend through the template cam plates I61 and I68 and are threaded into the end plate I66. The cam plates I61 and I68 are located so that they can be employed as a control template for two differing forms of glass blank to be ground and whereby a change-over can be quickly effected without too much downtime of the machine. The template cam plates I61 and we are initially secured together, previous to being secured with the plates I65 and I66, by means of screws H6. The template cam plates I61 and I66 are shown as being of the same width but differing in length. However, template cams of different shapes and/or sizes can be substituted 9 for the templates I! and I08, depending upon the size and/or shape of work to be edged.

The end plate I86 is centrally formed to receive the adjacent end of shaft 95 and is preferably slotted as at II? in which are secured keys III! held in place by set screws lit. The periphery of the shaft 95 is provided with complementary keyways I20 for receiving the keys I It to thereby interconnect the shafts 95 and 96 so that they rotate as a unit.

The shaft 95, journaled in bearings 9! in gear case 98, is extended through the lower capping plate 99 to afford a connection to a stationary gland I 2|. This gland is connected by a pipe I 22 with a conventional vacuum system, generally indicated at I23 in Fig. 1 and which includes a tank I2 3, pump I25 and motor I26. The pipe I22 is, more particularly, connected to an electrically actuated control valve 527 that is connected to the tank I24 by a pipe I lit and thus controls communication between the pipes I28 and I 22 and to the gland 22!. Said gland is, as shown in Fig. 18, provided in its ends with suitable packing elements I 29 and with the gland intake port I30. The outer surface of the shaft is provided with an annular groove IEI in registration with the port I38 of the gland, said groove communicating with the axial passageway I I4 through a plurality of openings I32. When the control valve I2? is open, the vacuum established in tank I26 will create a reduction in pressure in pipes I28 and I22, gland It! and passageway IM of the spindle assembly which reduction in pressure extends to the work supporting assembly I to maintain the work in position thereon during grinding, as will be more fully hereinafter described. The lower end of the shaft is closed by a plug I33 and is externally threaded to receive a nut its which supports a bearing washer I35 for the gland MI. The gland IlI is secured against rotation by means of a bifurcated bracket I36 which is secured to and depends from the shelf 2%.

The upper end portion I31 of shaft 9% is reduced in diameter to receive an annular splash guard i313 supported on the shoulder I39. This splash guard is secured in position against said shoulder by a sleeve I ltpressed onto the end It; of the shaft.

The work supporting assembly or holder I comprises a work block MI for supporting the glass blank J, a vertically movable plate I t2 and a channeled collar I i-3 carrying said plate, the work block MI having a centrally formed recess M4 in the bottom surface thereof in which the upper end of shaft 96 is received. The work block is fixed to the shaft by screws I45 which are located in said block (Fig. 19) and threaded into the end of the shaft.

The work block MI is provided in its upper surface with recesses Hit, and has suitably secured to its upper surface a layer I ll of soft material, such Ebonite or the like, having openings I48 in re istration with the recesses I45. Each recess nunicates with a central bore I59, drilled Idii c longitu lnally through the work block, by means of ti sverse passageways I513. The bore ltd is closed. at ends by plugs I EI and, by means of a centrally disposed hole I52, is connected with the passageway I I l extending axially through the shafts 95 and and in communication with the glan I2! at the lower end of shaft t5. By connection of the said gland to the evacuating system I22, as has been explained, the glass blank J will be firmly held upon the work block MI during the grinding operation.

As shown in Fig. 18, the vertically movable plate I42 and supporting collar M3 are disposed beneath the work block MI and are so interrelated as to move as a unit. The channeled collar I43 has a shoulder I53 formed in its upper surface against which the plate I42 is received, said plate being secured thereon by screws I5 1, as shown in Fig. 20. The collar may thus be actuated to move the plate Hi2 vertically toward and away from the work block I lI. To afford a bearing surface for reciprocal movement of the parts, the collar has a sleeve I55 contained therein which is slidably mounted on the sleeve I40 on shaft 96.

The plate I42 is movable relative to block MI to locate vertically disposed work retaining fingers E56 either above or below the upper surface thereof. The fingers Ifit have tapered upper end surfaces I51 which receive the rough glass blank J during its initial placement on the work block MI, said fingers being movable in openings provided by notches I 58 (Fig. 4) formed in the sides and ends of the block I II and plates IE9 which close the same. The lowermost ends of the fingers I56 are notched, as at I 60, to enter corresponding notches ItI in the plate I42 so as to be slidable therein according to the dimensional size of the block and so that the said fingers can be adjusted to move freely within the openings afforded by the notches I58. The glass blank J is thus initially located, with reference to the surface of the block by means of the fingers let, and subsequently lowered onto the surface layer It? as the collar and plate are moved downwardly beneath the block and along the sleeve I40.

Within the channel I82 of collar M3, is a split ring I63, the halves of which are secured to-" gether in a conventional manner by screws I64. The assembled ring IE3 is connected by means of diametrically extending pins Itli to an actuating lever I56 intermediate the ends thereof. The association between the collar Hi3 and ring I53 is such as to effect movement of the collar in a vertical direction while preventing rotary movement of the ring with the collar. The lever I 66 comprises two parallel bars It] disposed at opposite sides of the ring Itt and pivotally supported at its rear end by a transverse rod I68 mounted at its ends in a bracket its secured on the wall 322 of the platform 2! (Fig. 18). The forward ends of the bars ItI are interconnected by a transverse rod I'It in order that said bars will move as a unit. Each of the bars is provided with a slot III (Fig. 20') in which is located a slide block I'IZ drilled to receive the pins I of the ring H53. Thus, as the lever Itii is swung vertically upon rod Hit, the positional relation of said lever and pins it's will be compensated for by sliding movement of the blocks I12 in their respective slots HI.

Upon movement of the forward end of the lever I66 in an upward direction, the ring I63 raises the collar I43, and with it the plate I42 carrying the locator fingers Ifit. Preferably, the

extent of this movement is sufhcient to project the tapered ends I57 of said fingers above the elevation of the block IM for convenient placing or removal of the glass blanks or finished plates;

while in their lowermost position, the tapered ends Iii-l" of the fingers I56 are well below said top elevation or the block.

The lever I65 is actuated during the manually controlled phase of the machine cycle or while a finished plate, such as that indicated at B in Fig. 5, is removed from the support assembly I and is subsequently replaced by a rough blank J, as best seen in Fig. 1. When making this substitution, the operator raises the lever I66 and simultaneously places a temporary control on the operative system of the machine by means of a hand lever I13 or an interconnected foot treadle I14. As shown in Fig. 1, the lever I13 and treadle I14, which constitute the manually operable control means K, are interconnected by means of a link I15. The hand lever I13 is fixed to a shaft I16 which is rotatably mounted in the front wall 32 of the platform 2I intermediate its ends. Fixed to the inner end of shaft I16 is a transverse crank arm I11 which carries at its outer end a crank pin I19 projecting toward and beneath the rod I of lever I66 so as to lift the forward end of the lever I66 when the hand lever I13 is swung in a clockwise direction (Fig. 7). This movement, being transmitted to the collar I43 through the lever I66 and pins I of ring I63, causes the plate I42 and fingers I56 carried thereby to raise the glass blank or plate from the work block I4I to an elevated position for removal. The treadle I14 is carried by a shaft I18 secured in the wall of the base 22 and in general vertical alignment with the hand lever I13.

While either the hand lever I13 or treadle I14 is swung clockwise, and before the fingers I56 engage the glass blank or plate, a horizontal arm I extended from the link I15 contacts and opens a switch I8I which is mounted on one of the legs 21 of the shelf 26. The switch I8I forms a part of the control circuit for the evacuating system I23. More particularly, the switch IOI controls the electrically actuated valve I21 (Figs. 1 and 22) which is positioned between the pipes I22 and I28 from the tank I24 to the gland I2I. As previously set forth, the said gland encircles the end of shaft 95 of spindle assembly 31 and consequently when the valve I21 is closed by actuation of switch I8I, the vacuous condition created in the pipes I22 and I28, passageway H4 and block I4I of the work holder, is destroyed, whereupon the glass blank or plate may be removed. On the other hand, when the hand lever I13, or treadle I14, is released, the arm I80 will be moved away from the switch I8I and the valve I21 opened to reestablish the vacuous condition, and the vacuum created within the recesses I46 of work block I4I will draw and hold the newly placed rough blank J securely against the surface layer I41 of the work holder.

Reversal of movement of the manually actuated hand lever I13 or treadle I 14, will release the switch I8I from the control of the arm I80 and also permits the bar I11 to lower the lever I66 whereby the plate I42 and collar I43 will withdraw the tapered ends of the fingers I56 from above the block MI and allow the glass plate to settle into position on the upper surface thereof. To insure automatic return of the manually actuated members I 13 and I14 to inoperative position upon the release thereof by the operator, a spring I82 is connected between the arm I80 and base 22 of the machine to reverse the movement of the hand lever and treadle (counterclockwise) when they are released.

Provision is made for automatically starting the grinding cycle of the machine when the hand lever I13, or treadle I14, is released after the finished plate has been removed from the work holder and a rough blank secured by vacuum thereto. In Fig. 2, the hand lever I13 is illustrated by full lines when in inoperative position and by the broken lines when moved to operative position. The lever has formed thereon a bifurcated extension I83 between the side portions of which is received a dog I84 eccentrically supported on a pintle I85 and having a flattened end I86 normally abutting the wall I81 of the extension I83. When the hand lever I13 is located in full line position, the outer end I88 of dog I84 is positioned above the adjacent end of a trip bar I89 carried on a pivot pin I90 secured to the wall 32 of platform 2 I. During turning of the lever I13 clockwise to the position indicated in broken lines, the dog I84 will strike the end of the trip bar I89 and the said dog will swing upwardly about the pintle I85, until it passes beneath the trip bar I89.

However, when the hand lever I13 is released so as to return to its original position, the end I86 of the dog, in its abutting relation with reference to the wall I81, resists movement of said dog and as the opposite end I88 engages the trip bar I89, rotation of said trip bar upon pivot pin I90 will be effected. Upon such rotation, the opposite end of the trip bar will be moved into contact with the plunger I9I' of a limit switch I9I. The switch I9I is included in the control circuit of the drive motor I92 for the machine. Thus, when the dog I84 is moved upwardly, the trip bar I89 will be rotated to actuate the limit switch I9I; and, as the dog disengages the bar, the said bar, under the influence of a spring I93, will return to its normal position and the cyclic operation of the machine will have been initiated.

During each operating cycle of the machine, the carriages 4I and 42 of the grinding units E and F respectively are caused to move longitudinally inwardly toward the work supporting assembly I and work J mounted thereon by the rotation of a cam I94 (Fig. 8), said cam also subsequently effecting the outward movement of the grinding units to return them to their starting positions. When the grinding units reach the limit of their inward movement, they are brought into operative engagement with the template I01 carried by spindle assembly 31 and remain in engagement with said template during the grinding cycle.

The cam I94 and spindle assembly 31 are driven through an interrelated mechanism from a drive motor I92, with a differential gearing being interposed so that the template I01 will be caused to rotate one and one-half revolutions while the cam I94 rotates one complete revolution. The rotation of the template I01 will of course be imparted to the work block MI and work blank J, the reason for rotating the work blank one-half revolution more than the cam I94 being to effect an overlapping of the grinding action at the completion of the grinding cycle.

It has been found from actual experience that if the work block or holder MI is located diagonally, as illustrated in Figs. 4 and 7, instead of in alignment with either the longitudinal or transverse axis of the machine, the glass or other work blank J can be more easily placed thereon and removed therefrom since it results in a more physically natural movement of the operators hand during loading and unloading. Therefore, at both the beginning and end of the machine cycle, the work holder is preferably disposed diagonally as in Figs. 4 and 7.

In order to illustrate somewhat more in detail the relative differential of rotation established and maintained between the grinding unit's E and F on the one hand and the work supporting carriage I on the other, or more particularly between the cam I M and template III'I, there is indicated in Fig. 6 a series of radially changing arrows a and b representing respectively the glass blank J and cam I94. The succeeding positions assumed by the glass blank and cam during one complete machine cycle are diagrammatically shown at c to is inclusive.

The letter designates the relative positions "of the glass blank and cam at the start of the machine cycle, while the letter is designates their relative positions at the completion of the grinding cycle. It will be seen that between positions 0 and 7c, the glass blank J rotates one and onehalf revolutions while the cam I94 completes one revolution. Upon placing of the machine in operation, the glass blank J will be revolved clockwise approximately 45 degrees, while the cam I94 is being rotated only approximately 3i) degrees to the positions indicated at (1. During this time the grinding units will be moved inwardly into engagement with the template I97 and the grinding wheels G and H into contact with the glass blank J. Upon continued rotation of the work holder and cam and during movement thereof from positions 0, to positions h, the edges of the glass blank will be subjected to the action of the grinding Wheels and Will complete one full revolution while the cam I94 turns through substantially two-thirds of a revolution. As the work holder rotates from position h to position a, it moves into its second revolution While the camhas substantially completed its first revolution. During this period, the grinding operation will continue approximately 45 degrees beyond the initial point of contact of the grinding wheels with the glass blank to assure that the entire edge of the glass blank has been properly ground. Upon movement of the work holder and cam from position 7' to position is, the grinding wheels will be moved outwardly away from the work and back to starting and rest positions.

As shown in Fig. 1, the drive motor I 92 is mounted on the base 22 and drives a hydraulic transmission unit I555 through belts I95 trained about the respective pulleys of the motor I92 and transmission unit :95. The output shaft of the unit 99 is coupled to a pair of worm drives, generally designated and I93 (Fig. 14) which drive the work spindle assembly 3'! and cam Ilil respectively. While it is preferred that the worm drives till and its designed to produce clockwise rotation of their respective driven members, it is possible, and may at times be found advantageous, to cause said worm drives to effect rotation of the work spindle assembly 31 and cam I9 2, in a counter-clockwise direction.

The horizontally aligned shafts I99 and 299 of worm drives I9! and I98 preferably are 0perated from the output shaft of the transmission E95 by means of a chain drive comprising the sprockets 29I and 22d? and the chain belt 293, which passes through a cored opening 294 provided in the shelf .29. The sprocket ZDI is associated with the transmission i95 while sprocket 292 is carried by couplings 295 keyed. to th ex tended and opposed ends of the shafts I99 and 299. These shafts are provided with worms 2% and 2m respectively, the shaft I99 and worm 296 being journaled within the gear case 99 mounted on shelf 26, while the shaft 200 and 14 worm 291 are journaled in a similar gear case 299. Preferably, the worm drives I 9? and I98 have a speed ratio of 60-40.

' The worm 298 carried by shaft I99 is supported within the case 93 in meshing relation with a worm gear 2% (Fig. 18) mounted on the shaft portion 99 of the spindle assembly ill and secured thereto by a spline key 2H3. Rotation of the spindle assembly and work holder is thus eifected by the drive mot-or I92 and will be of the desired speed according to the gear ratio as to rotate the work supporting carriage I approximately 45 degrees before engagement of the grinding wl'ieels G and H with the edges of the work blank 5 as explained above in the description of Fig. 6.

The worm 29? is in meshing relation with a worm gear 2!! carried on a vertically disposed shaft journaled in the gear case 298 (Fig. 8) and having keyed to the upper end thereof the cam 59d. Mounted for rolling engagement with the edge of cam We is a roller 2m, rotatably carried by a shouldered stud 254 in a suspended arrangement on a lever arm 2H5 (Fig. 14), to reciprocally swing said lever arm during one complete rotation of said The lever arm 2I5 is journaled at its rear end on the upper end of a vertical post 2E8 (Fig. 10) mounted on the shelf 29 and having a shouldered portion 2i! on which the lever is supported, and a threaded end 2H; for receiving a retainer nut 2I9. Said lever arm 2I5 is normally urged inwardly to maintain the roller 2I3 in engagement with cam I94 by means of an articulated linkage, generally indicated at 229. In th construction shown, this linkage 229 comprises a horizontal slide bar 22I with which the forward end of lever arm 2I5 is slidably associated, and a link belt 222 connected at one end to a plate 223 carried by slide bar 22! and at its opposite end to a weight 224 through a cable 229.

The forward swinging end 226 of lever arm 2I5 is slidably supported in a block 22'! having a pin extension 223 which is located in a socket 229 formed in the slide bar 22I intermediate the ends thereof and by which it is pivotally associated therewith (Fig. 12). Said slide bar is supported at its opposite ends in brackets 230, secured to the shelf 26, and is slidable therethrough upon rotation of the cam I9 l.

Th link belt 222 is trained intermediate its ends about gears 23E and 232. The gear MI is mou ted on a flanged collar 233 journaled by the needle bearing and supported on the annular shoulder 29% of the shaft portion 95 which constitutes the lower portion of the spindle assembly 9"! (Fig. 18). Also carried by the collar is a cam 239 which rotates as a unit with the gear 291. The idler gear 232 is rotatably supported on a shoulder 239 on post 2| 6 beneath shoulder 2H which sup-ports the lever 2H9 (Fig. 10). The weight 225 is located within one of the pillars 2d of the machine as shown in Figs. 3 and 8, and the cable 225 carrying said weight passes over a sheave 23'! rotatably mounted on a horizontal shaft 239 journaled in the walls of the pillar.

The cam Hit comprises a substantially flat plate of irregular outline having a high or peak area (Fig. 6A) and a diametrically opposed low or dwell area 299a. interconnecting these areas is a descending cam surface portion 239!) and a subsequent rising portion 2390. Thus, as the cam rotates in a clockwise direction from the full line position in Fig. 6A, the follower roller 239 along the descending cam surface 239D t the dwell area 238a; this action being similar in radial motion to that of the arrow b (Fig. 6) from position 0 to position e. Upon continued rotation of the cam, the roller 2|3 will leave the dwell area 239a and follow along the rising cam surface 22-90 to the peak area 239 which completes one revolution of the cam and corresponds to position It in Fig. 6.

In rolling engagement with the peripheral edges of the cam 235 are two rollers 245 and MI depending from the forward ends of bars 242 and 243 and journaled on respective shafts 244 and 245 (Fig. 11) that are secured in the said bars. The bars 242 and 24-3 have integral tubular mounting sleeves 245 at the rear ends thereof which are rotatably supported on vertical posts 241 mounted on the shelf 25 (Fig. 18).

The free forward ends of the bars 242 and 243 are pivotally connected by pins 243 and 249 to the adjacent ends of links 259 and 25| respectively, which are carried at their opposite ends by the base members 43 of the carriages 4| and 42 (Fig. 1 As herein shown, each link 259 and 25| has a plurality of holes 252 formed therein adjacent the end thereof and a pin 253 is passed through one of the holes according to adjustments which may be found advisable when setting up the machine. Th pin 253, in each instance, is secured by a set screw 254 in a plu 255 having a threaded end 256 by which said plug is connected to the base member 43. The links 259 and 25| are free to swing about the axis of their respective pins 253 in complementary radial movement to the bars 242 or 243 as said bars are actuated by oscillation of the cam 235.

Through the interrelation of the bars 242 and 243, the links 259 and 25| and the carriages 4| and 42, the rollers 249 and MI are normally urged into engagement with the cam 235. This is accomplished and the weight of the carriages 4| and 42 counterbalanced by means of cables 251 and 253 secured at one end by studs 259 and 269 to the respective bases 43 of said carriages and having connected to their opposite ends the weights 25| and 262. The respective weights for the carriages are located, as the weight 224, in the supporting pillars of the framework 20. Thus, the weight 23! for the carriage 4| is located in the pillar 24, in the opposite corner from that pillar 24 in which the weight 224 is located and the cable 251 thereto is trained over a sheave 263 supported on a shaft 254 journaled in the walls of the pillar. In a corresponding manner, the weight 262 for the carriage 42 is located in one of the pillars 23 and the cable 258 therefor is trained about a similar sheave 265 supported on a shaft 266.

The cam 235 is driven from the cam 194 through the linkage 225 first in one direction and then the other to effect the inward and outward travel of the grinding units E and F at the beginning and end respectively of each machine cycle. The relative positions of the cams I94 and 235 at the beginning of the machine cycle are shown in Fig. 8 and during the grinding operation in Fig. 9. These relative positions of the two cams are also illustrated diagrammatically in full and broken lines in Fig. 6A.

The cam 235 comprises a substantially flat plate including a central body portion 251 provided with diametrically extending wing portions 258a and 2681) having oppositely facing cam edges 16 2680 for engagement by the rollers 249 and I. Upon rotation of the cam I94 in a clockwise direction from its full line position in. Fig. 6A to its broken line position, the cam 235 will likewise be rotated in a clockwise direction from its full line position to its broken line position by the linkage means 229. Simultaneously, the follower rollers 249 and MI will move inwardly along the cam edges 2380, and the weights 26| and 262, acting through cables 251 and 253 to the carriages 4| and 42, and their respective links 259 and 25|, will effect movement of the carriages 4| and 42 toward each other and the grinding wheels G and H into grinding engagement with the work piece J. During the inward movement of the carriages 4| and 42, the spindle assembly 31 and work piece J will rotate from position 0 in Fig. 6 to position 01.

Carried by the carriages 4i and 42 are annular follower plates 239 and 213 adapted to engage the peripheral edges of the template I91 when the grinding units are moved inwardly to grinding position. These annular follower plates 269 and 219 are of a predetermined diameter according to the diameter of the grinding wheels G and H, so that they will engage the template I91 and thus limit the inward movement of the grinding units before the rollers 249 and MI complete their inward travel along the cam edges 2680. Thus, the follower plates 269 and 219 act to hold the rollers 245 and MI from engagement with the cam 235 so that during the grinding cycle, the inward and outward movements of the grinding units will be controlled by the cooperating action of the template m1 and follower plates 269 and 219 without interference by the rollers 249 and 24| which are maintained in a floating position. Consequently, during the actual grinding cycle, as indicated between positions e and :i (Fig. 6) reciprocal movement of the grinding units will be produced by rolling engagement of the followers 259 and 219 along the peripheral edge of the template I91 and independent of the initial and subsequent control of the cams I94 and 235.

When the cam I94 has rotated so as to enter the remaining sixth of its rotation, the roller 2 l3 will followed the rising cam surface portion 2390 thereof and, through the lever 2|5 and linkage 229, produce a counter-clockwise rotation of the cam 235. The cam edge surfaces 2680 of the wing portions 238a and 2582) will now pick up, in rolling engagement, the rollers 249 and MI, whereupon the bars 242 and 243 of each related carriage, will be swung outwardly to remove the followers 269 and 219 from engagement with the template I91. This constitutes completion of the grinding cycle, but the machine cycle is not complete until the cam I94 completes a full revolution and returns to its starting full line position in Fig. 6A, at which time the grinding units have been moved outwardly to their starting position.

The follower plates 269 and 210 (Figs. 14 and 15) are rotatably supported on similar, vertically disposed shafts 21| journaled in the outer ends of horizontal brackets 212. The brackets 212 are secured at their inner ends to the flanged outer ends 213 of bars 214. The flanges 223 are slotted as at 215 to receive fastening bolts 216 which are threaded into the adjoining face of each bracket 212 (Fig. 15).

The bars 214 are carried on the base 43 of the respective grinding unit E or F by means of a washer 211 and a nut 218 associated with a threaded stud 219 which is secured in the base of the respective carriage:4 I .or42'. Asshown in :Fig. 13,,each; bar .274. is, supported at .its 'outerend by a cross plate sac affixedto depending lugs 28! from thezbase 143... The-opposite sides of the bar are en aged by; set, screws282 threaded through lugs 28! and helclfrom rotation bylock nuts 283. By adjustingthe'set screws 282, the bar 2 may be loca-ted in or-at an angle to the longitudinal axis oi the machine. Eachbracket 212, carries a horizontal stub shaft 28,4 received in a socket285 in the respective bar; 214-; in parallel alignment to its longitudinal axis but eccentrically with respect to--its horizontal axis; as shown, in Fig. 15. By looseningthe bolts 216,7the bracket-2120f the related follower plate 269 or 2-1llcan be shifted angularly untilthe plate-is brought into a substantially horizontal plane-so; as to travel evenly alongithe peripheraledgeof the template I01.

{Whensetting up the machine for" any particular shape of template lfi's' the grinding-units are usuallymov ed inwardly until the follower plates ZuS and 21B; contact the edgesof the-template LIL-while the same isstationarysothat the periph eral grinding surfaces 'ofthe grinding wheels G and'I-I; will be satisfactorily disposed in contact withthe eclges of a -test workrpieceiof the desired predeterminedsize Any necessary adjustments may t hen be effectedby loosening the clamping shaft 911 to .free the yadjustingscrew 85: from the jaws--94 and .igtl rning screw -25 by its handle 85 tomove the slide member liialong and within the guideway 58. The grinding unit E and T5 m ay thusbe individually located to obtain the-most effective edging and/ or .beveling. ofthe glass plate, after which theishafttt is again turned-V to replacethe' jaws 92 in clamping relan abe tthe r w it t Upon completion ofgthe machine cycle, as de: termined. by one revolution of the cam let; the leverizlb will be swung; to: urge the slide ,bar 22 I rearwardly inbraclcets 215B. llhebarcarries on its underflsurrace a block 2.8-6 havin a sloping area 23} adapted to;engage the-wplunger; 2880f a limit switch 289. -;'iihe limit switch 229 E is secured on theishelf-fifi and, when-actuated,interrupts a con- ??Ql circuit for: the;;power;,oircuits.. tothe drive motor, [92 and .consequently when the bar 221 moves to the position shown in Fig. l-, the switch 28!) is opened and operation of the machine ceases.....

A coolant systemLg-enerally designated 2% in d ps e ls implying the usual: liquid e tubing 29.7.

t isrdrained therefrom iquid-baclr; to the reservoir 2;: flSllblflSOQSI'l-tlY rec rculated whens t g devices by the pump 29!.

through usual filterin I r and Hendthence to, the work piece Jifl hissystem comprises a pump- 2 lil driven-by a-motor 292.- pipe 293 runs from.

connecting with thenozzles 236 may 'becarried by the. .33 y or the support members 59 re -formedintegrally with- When 13119 liquid overflow;

peningsfilltto pipes ltd! adapt.-,

The electrical controls and circuits for the mechanical and vacuum systems are illustrated in the wiring diagram in Fig. 22.- As therein shown, a master switch 362 is located between the positiveinain-linettS and the various control circuits for the main drivemoton 1 F22; the vacuumcontrol valve 52?; the motor I26 for operating the vacuum system H23 by which the Work. piece J is secured to the Work support I; and the motor 292 for operating the coolant system 29!] which supplies coolant liquid to the grinding Wheels G and H and Work pieced clurin grinding. When closed, the master switch 3G2 completes a circuit to the normally open limit switch l8| by lines3ll4 and 365 to control the operation of the vacuum system valve 21; to the coil 306 of starter relay switch Sill-for the motor [26 through line 388 r for operatin the vacuum system I23; to the i normally open limit switch I91 to control energization of the coil 309 of the starter relay switch em for the main drive motor Hi2 through lines 3%; 3H and 3l2 through the emergency, nor mally closed switch 31?; and to the coil 3M of the starter relay switch 3l5 for "the motor 292 forthe coolant system 29d by line 3 l t.

' A second master switch fill connects the'coils M8 and 3m of the starter relay switches 320 and 32! for the motors 322 and 323 of the'grinding units E and F to the positive main line 303' by thelines 3M anol324 and branch lines 325. When master switch 3|? is"closed, a circuit from the positive-main line 383 will be completed to" the coilsiil and M9 bylines 3M, 32 land 325,"to

" energize the relayswitches S20 and32l and close their double contacts :328 and 5529 respectively, and to the negative main line 330 by lines 33! and Upon closure or the double contacts I 328'and 322 of the relay'switches 32B and 32!,

circulits will be created from positive mainliries 333 and 33:3 to the-double contacts 328 and 329 by lines'stii anol336 and thence to the motors 322 and .323, completing said circuits to a negative main line car by lines fitfi and 338. Preferably, normally closedswitches'32i5and 32? are interposed in 'the branch lines 325 so thatby ac-' Simultaneously-the vacuumsystem I23 and the coolant system 2 so are placed in operation. Thus, the switch 322 energizes the coil 3% by lines 3M and 3%, completing a circuit through said coil to thenegative main line 330 by lines 3 39 and 33! andactuating the relay switch 3s? to close the double contacts 34! thereof. The double contacts 3%! complete service circuits from the positive main lines 333 andtte to the motor iZE of the vacuum-system l23 through lines 322 and 343,

said motor being connected to the negative main line 337 by lines 3 54 and 338.. The circuit from the master switch 302 also energizes the coil 3M of the relay switch (M5 by lines 394 and 3i 6, completing a circuit through the coil to the negative main-line 335! by line 3&5 and actuating the relay switch 3 l 5 to close the double contacts 356 thereof. Closing of-the double contacts 346 completes circuits to the motor 292 forthe coolant system 290 from the positive main lines 333 and 334 by lines 341 and 348 and from the motor to the negative main line 331 through line 349. The pump I25 of the vacuum system is now driven to evacuate the tank I24, and the pump 29I of the coolant system is also driven to supply liquid, as previously described, to the grinding wheels G and H of their respective units E and F.

In the operation of the machine and when either placing a rough work piece upon the work holder at the beginning of the operation or removing the finished work therefrom at the completion of the operation, it is necessary that the switch I8I be held closed by the operator. To do this, the operator either grips the lever I13, usually by the right hand, or steps upon the treadle I14 to actuate the lever through the link I15. As the link is shifted in a vertical direction by either member, the arm I80 carried thereon engages and closes the switch NH.

The closing of the switch I8I closes contacts 350, thereby completing a circuit from the positive main line 303 though switch 302, line 305, contacts 350 and line 35I to the valve I21 and thence to the negative main line 330 through lines 352, 340 and 33L While the structural details of this valve are not shown, their function is well known in the art, it being understood that upon energization of its electrical components, the valve will close communication between pipes I22 and I28 of the vacuum system and reduce the vacuous condition in the gland I2I. Since the switch I8I controls the valve I21 to temporarily destroy the vacuous condition in the gland I2I and work support block I4I, the operator can easily remove the finished plate with his left hand and, while still engaging the lever or treadle, substitutes a rough blank which is supported on the locator fingers I56 of the work holder which have been elevated by rotation of the hand lever I13, through lever I66 which is swung upwardly by engagement of the lever bar I and the pin I19 carried as a part of the hand lever, as previously set forth. Upon release of the hand lever I13, it is swung counter-clockwise by the spring I82 to cause the arm I80 to move from contact with the plunger of the switch I8I to open the same. The fingers I56 then lower the glass blank J onto the surface layer I41 on the upper surface of the block MI and the dog I84, carried by the lever I13, engages the trip bar I89 to actuate the limit switch I9I. Upon momentary closure of switch I 9|, a circuit is created from the positive main line 303 through switch 302, lines 305 and 3, contacts 353 of the switch I9I, line 3I2 and normally closed switch M3 to the coil 309 of the starter relay switch M0, and thence to the negative main line 330 by lines 354 and 33I. Closing of the contacts 353 also completes a circuit by line 355 to the timer relay 356, through said timer and the closed contacts 351 of the emergency switch 3I3 by line 3I2 to the coil 309 of the starter relay switch 3 I0.

The timer 356 is adjusted to maintain the circuit through the coil 309 closed until, by rotation of the cam I94 and the related radial movement of lever arm 2I5, the slide bar 22I has removed the block 286 from engagement with the plunger 288 of limit switch 289, allowing the contacts 359 thereof to close. The limit switch I9I and the timer 356 having opened, the closed limit switch 289 completes the circuit through lines 305, 350, 36I, 358 and 3I2 to the coil 309 and thence through lines 354 and 33I to the negative main line 330. The coil 309, while energized, actuates the armature of the starter relay switch 3I0 to close the double contacts 362 to complete circuits from the positive main lines 333 and 334 through lines 335 and 336 and 363 and 364 to the motor I92 and thence to the negative main line 331 by line 365. Said switch I9I thus starts the automatic machine cycle by the main drive motor I92 and, through the hydraulic transmission unit I95, the worm drives I91 and I98 rotatively drive the cam I94 and the spindle assembly 31. The cam I94, through the lever 2I5 and the linkage 220, causes clockwise rotation of the cam 235 to move the grinding units E and F toward one another and bring the grinding wheels G and H into engagement with the glass blank J, interposed therebetween.

More particularly, the cam I94, through roller 2 I3 and lever 2 I5, shifts the slide bar 22I within brackets 230, and causes clockwise rotation of the gear 23I as the link belt 222 moves in meshing relation therewith by movement of said bar and imposed draft of the weight 224. Rotation of the said gear and the cam 235 carried thereon causes the rollers 240 and HI to follow the cam surfaces 2680 of the cam 235, causing the pivotally jointed bars 242 and 243 and links 25I and 252 to swing in their coacting movements. As the rollers 240 and HI roll inwardly along the cam surfaces 2680, the weights 26I and 262 urge the grinding units E and F toward one another until the follower plates 269 and 210 are brought into contact with the opposed edge surfaces of the template I01.

In moving into contact with the template I01, the follower plates 269 and 210 engage a moving surface since, as the cam I94 starts to revolve, the spindle assembly 31 also starts to revolve. Due to the speed differential imposed on the associated worm drives I91 and I98, and the worms 206 and 201 and gears 209 and 2 which constitute the same, rotation of the spindle assembly 31 is relatively more rapid. In fact, while the cam I94 is turning sufliciently to deliver the units E and F to the work and the follower plates 269 and 210 to the template I01, the shafts 95 and 96, constituting the assembly 31, have been rotated somewhat in advance to turn the support assembly I, the glass blank J thereon and said template I01 until the longitudinal axes of said template and glass blank coincide substantially with the longitudinal axis of the machine as previously described in connection with Fig. 6. Grinding of the blank to the desired finish continues while the cam I94 revolves through substantially five-sixths of its revolution. Thus, as the template I01 approaches completion of the first half of its second revolution, the cam I94 approaches completion of one revolution. The gearing ratio of one to one and a half, established by way of example, definitely assures overlap grinding of the blank J so that the grinding is carried well beyond the initial points of contact and separation of the wheels G and H to complete the grinding cycle is accomplished in ad- Vance of the completion of one machine cycle.

During movement of the cam I94 toward completion of one revolution, the roller 2I3 swings the lever 2I5 rearwardly, causing the slide bar 22I by the link belt 222 to revolve the gear 23I and cam 235 counter-clockwise, thereby moving the rollers 240 and 24I outwardly along the cam surfaces 2680. As the rollers 240 and I follow the said surfaces of the cam 235, the bars 242 and 243 are swung to urge the links 250 and 25I outwardly and to move the grinding units E and F for raising the finished work piece from the work holder and for subsequently lowering a rough work piece into position thereon, means for creating a vacuum within the work holder to maintain the work piece in position thereon during grinding, and means under the control of an operator for substantially simultaneously breaking said vacuum and raising the finished work piece from the work holder to facilitate removal thereof and for subsequently lowering a rough work piece onto the work holder and reestablishing the vacuum.

2. In an edge grinding machine of the character described, a rotary work holder comprising a vertically stationary support block for supporting a work piece thereon, a grinding unit comprising a rotary grinding wheel for grinding the edges of the work piece, a drive motor for the work holder, a starter switch for said motor, vertically movable means for lifting the finished work piece from the work holder and for subsequently lowering a rough work piece into position thereon, means for creating a vacuum within the work holder to retain the work piece in position thereon during grinding, and means under the control of an operator for substantially simultaneously rendering the vacuum means ineffective and raising the finished work piece from the work holder to facilitate removal thereof and for subsequently lowering a rough work piece onto the work holder, reestablishing the vacuum and actuating the starter switch to start the drive motor.

3. In an edge grinding machine of the character described, a rotary work holder for supporting a work piece thereon, a vertical shaft carrying the work holder at its upper end, a template carried by said shaft, a pair of grinding units including rotary grinding wheels, rotatable follower plates carried by the grinding units, means for driving the grinding wheels, means for driving said shaft and work holder, means for normally urging the grinding units inwardly to bring the grinding wheels into engagement with the edges of the work piece and the follower plates into engagement with the template, and means for rendering the last-named means effective to cause the grinding units to move inwardly and subsequently ineffective to cause movement of the grinding units outwardly at the completion of th grinding operation, comprising a cam freely rotatable upon said work holder shaft, follower rolls carried by the grinding units and engaging said cam, and means for rotating the cam first in one direction and then the other to cause the grinding units to move inwardly and outwardly.

4. In an edge grinding machine of the character described, a rotary work holder for supporting a work piece thereon, a vertical shaft carrying the work holder at its upper end, a template carried by said shaft, a pair of grinding units including rotary grinding wheels, rotatable follower plates carried by the grinding units, means for driving the grinding wheels, means for driving said shaft and work holder, means for normally urging the grinding units inwardly to bring the grinding wheel into engagement with the edges of the work piece and the follower plates into engagement with the template, means for rendering the last-named means effective to cause the grinding units to move inwardly and subsequently ineffective to cause movement of the grinding units outwardly at the completion of the grinding operation, comprising a cam freely rotatable upon said work holder shaft, follower rolls carried by the grinding units and engaging said cam, a second rotatable cam, drive connections between said second cam and first cam, and means for driving said work holder shaft and second cam with the relative speeds of rotation thereof being so related that the shaft will rotate more than one full revolution while the second cam rotates one complete revolution to cause an overlapping between the starting and completion points of the grinding operation before the grinding units are moved outwardly.

5. In an edge grinding machine of the character described, a rotary work holder for supporting a work piece thereon, a grinding unit comprising a rotary grinding wheel for grinding the edges of the work piece, a drive circuit including a drive motor, a starting switch and a control switch, means under the control of an operator for momentarily closing the starter switch to complete the circuit and initiate operation of the motor to rotate the work holder, means for opening said control switch to break the circuit at the completion of the machine cycle to stop the work holder, and a timer in said circuit actuated upon closing of the starter switch to maintain the circuit closed until the control switch is subsequently closed.

6. In an edge grinding machine of the character described, a rotary work holder for supporting a work piece thereon, a grinding unit including a rotary grinding wheel for grinding the edges of the work piece and movable toward and away from the same, a pair of templates secured in face to face relation for controlling the extent of grinding of the work piece, a rotary follower plate, a reversible mounting means for supporting said follower plate on said grinding unit in alignment with one of said templates when said supporting means is in one position, said mounting means including a member attachable to and reversible on said grinding unit and that is offset from the plane of rotation of the follower plate so that said follower plate will fall into alignment with the other of said templates when said supporting means is reversed, and means normally urging said grinding unit toward and the grinding wheel into engagement with the work piece and said follower plate into contact with one of said templates.

7. In an edge grinding machine of the character described, a rotary work holder comprising a vertically stationary support block having a surface for supporting a work piece, vertical locator fingers located in surrounding relation to said support block, means mounting said fingers in said location and for vertical movement from a position in which the tops of the fingers are below the work supporting surface on said support block to a position in which the fingers are above said surface, means for creating a vacuum within the work holder to maintain the work piece upon the support block during grinding, and means for raising said fingers into said second mentioned position to receive a work piece to be ground and for subsequently lowering said fingers into said first mentioned position to bring said work piece to rest upon the support block and substantially simultaneously actuating said vacuum creating means to maintain the work piece upon the support block during grinding.

8. In an edge grinding machine of the character described, a rotary work holder for supporting a work piece thereon, a grinding unit comprising a rotary grinding wheel for grinding the edges of the work piece and movable toward and 

